Subject: Re: DHCP and static configuration

From: James Kempf <[email-masked]>
Date: Sat, 11 Sep 1999 12:13:08 -0700 (PDT)

>
>
>How do I configure it if I want to flush DHCP down a long
>deserved toilet as an administrative nightmare, and use
>stateless autoconfiguration (IPv4 or IPv6)?
>

Stateless autoconfig for IPv4 has yet to be completely defined. There
is a draft about SLP on IPv6 by Erik Guttman, but it primarily deals
with service URL syntax and a few other items.

The problem here is that if I am a system admin and I am setting
up a network in which I need to provision which users get which
printers, I need to assign particular users and particular printers
to particular scopes. The "IETF approved" way of doing this
is DHCP, despite its warts.

>My nominal preference would be to have a UA on board the
>device that could ask "Where's my LDAPserver?" via SLP,
>and get its configuration from there, perhaps using its
>MAC address as part of the OID, after auto-discovering
>the base DN for the LDAP server (you can do this even for
>LDAPv2 servers).
>

Are you saying you want a UA on the printer?
I suppose if you need to find an LDAP server to determine configuration,
that would work OK. Why not simply put the SLP scope into the LDAP
attributes if you don't want to use DHCP? 

It seems like what you want is centralized service configuration via
LDAP rather than distributed configuration via HTTP and a web page,
which is how many printer/embedded print server manufacturers are
doing it these days. Is that so?

BTW, we have a draft for bridging service advertisements between
LDAP and SLP.

>Even if I had to eat the not inconsiderable cost of puting
>a keypad and an LCD on the printer, the LDAP server seems
>to be the correct parameter store for any device.
>

Many vendors are using a micro-HTTP server and a web page. The
amount of code necessary for an HTTP server is probably alot
less than for an LDAP stack (no ASN.1 parser needed). The
scenerio is that the sysadmin browses the printer and sets
any configuration required. No LCD and keypad neessary.

>I don't really want or need a keypad and LCD, though. I
>could, for example, define the object pointed to by my MAC
>address bearing OID to be an LDAP alias pointing to "Second
>Floor Engineering Printer In Far Corner".  This would let
>me swap out a dead printer with identical non-dead hardware,
>with no more than an alias assignment in the LDAP directory
>to be up and running.  I could even automate this, with a
>simple "desgnate me" service that the printer would request
>if it couldn't find its configuration.

What if you didn't have an identical printer? Then you would have
to go in and modify the LDAP record.

		jak

---

From: Terry Lambert <[email-masked]>
Date: Mon, 13 Sep 1999 11:21:22 -0700

> with service URL syntax and a few other items.

With respect, Windows 98 and Windows 2000 do IPv4 stateless
autoconfiguration, in the absence of a DHCP server.  And since
these platforms constitute the bulk of the clients for service
location, I would like to be able to drop a printer (or other
device) onto the network, and have it "just work".

> is DHCP, despite its warts.

This is interesting from an enterprise perspective; however
it seems rather weak to me that a printer I could walk over
to and shut off is somehow supposed to be "out of my control"
from an administrative perspective.  Worst case, I can go
over, open the paper tray, take out the paper I would have
printed on, and write what I wanted to print, using a pen.
8-).

I am much more interested in the small and medium business
use models, since they represent the largest untapped markets
still available today.

I am also rather convinced that very large companies don't
really represent much of a market for SLP enabled devices
for at least 4-5 years following universal deployment of the
infrastructure in new devices.  This is because they have an
entire amortization life cycle worth of existing hardware
infrastructure that has to be flushed before they can convert.
A small to medium business has much less inertia to overcome,
and can (and will) deploy new technologies faster.

It's much more important to these folks that "everything just
work", rather than accepting the administrative overhead that
comes with DHCP infrastructure.  I suspect that the majority
of these users will not have DAs, either.

> I suppose if you need to find an LDAP server to
> determine configuration, that would work OK. Why not
> simply put the SLP scope into the LDAP attributes if
> you don't want to use DHCP?

Does this count as static configuration?  If so, then I
have much less of a problem with the SA static configuration
requirement, since this would render it much less onerous.

> It seems like what you want is centralized service
> configuration via LDAP rather than distributed configuration
> via HTTP and a web page, which is how many printer/embedded
> print server manufacturers are doing it these days. Is that so?

I'd like to seperate the configured state from the device
so that I can place it in a central location.  A printer
is merely my "example device" for doing this.

It's useful to make this seperation, if only to allow the
clients of the device to properly configure their drivers.

> any configuration required. No LCD and keypad neessary.

Yes.  This is very annoying.  The UI varies between vendors,
and the state is not persistant or "cloneable" for multiple
devices.

An LDAP client for devices wanting to talk to a "configure
me" server is pretty trivial; an ASIC for implementing it,
given the TCP/IP-on-a-chip implementations that are
available today, would be pretty easy.

[ ... replacing a faulty printer without configuration of
      the new device ... ]

> to go in and modify the LDAP record.

Hopefully, we will specify what can be configured in a
device indepent way.

That, or buy only from vendors who adhere to cross vendor
configuration data standards.  8-).

-- Terry Lambert
-- Whistle Communications, Inc., an I.B.M. Company
-- [email-masked]
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